1. State Key Laboratory of Agrobiotechnology and Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
2. Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 11340 México Distrito Federal, Mexico
3. Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China